Switch and signal control system for railroads



Nov. 17, 1942. A. LANGDON ET AL 2,302,033

SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Dec. 26, 1940 10 Sheets-Sheet 1 10MB 10x15 5 L5 an? sate 4 14x15 1 B IGNB lXB 1 mvimons I Aggngdon and EBHitchcock THEIR ATTORNEY V I Nov. 17, 1942. A, LANGDON. ETAL 2,302,038

SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Dec. 26, 1940 10 shee ts sheet 2 INVENTORS A l ngdon and FBHitchcock THEIR ATTORNDEY Nov. 17,1942. A. LANGDON Em ,302

SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Dec. 26, 1940 10 Sheets-Sheet 4 2219 FIG-.11).

INVENTORS A.Lo.n don and FBHitchcock THEIR ATTORNEY Ndv. I2, 1942. A. LANGDON arm.

SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Dec. 26, 1940 10 Sheets-Sheet 5 INVENTORS Alg$ngdon and FBHi'Lchcock I'HEIMQQ Y Nov. 17, 1942.

A. LANGVDON ET AL SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Dec. 26, 1940 1d Sheets-Sheet e Y EBHitchcock 5 Y M M d T R Nm 0 w H mm A d R m m L T A Nov. 17, 1942. A. LANGDON ETAL 2 0 SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Dec. 26, 1940 10 Sheets-Sheet '7 INVENTOR5 angdon and EB. Hitchcock THEIR ATTORNEWZZZV' PIIIL Nov. 17, 1942. ALANGDON ETAL SWITCH AND SiGNAL CONTROL SYSTEM FOR RAILROADS Filed Dec. 26, 1940 l0 Sheets-Sheet 9 Fl 6.7. A.

9 llllll i I WH Q 2 mm N A 2 m G )x N w n 8 I, 2 9 .m

o I c 4H Hm S Y RF E O .N TdM N O Ea mm A ar m n w a T A Nov. 17, 1942. A. LANGDON ET AL SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Dec. 26, 1940 10 Sheets-Sheet 1O INVENTORS ALgmgdon and FBHitchcock 7M 44. MW THEIR ATTORNEY I Patented Nov. 17, 1942 UNITED STATES PATENT OFFICE swrron AND SIGNAL CONTROL SYSTEM FOR RAILROADS Andrew Langdon, Brighton,

and Forest B.

Hitchcock, Greece, N. Y., assignors to General Railway Signal Company, Rochester, N. Y.

18 Claims.

This invention relates to switch and signal control systems for railroads, and it more particularly pertains to a system where the manipulations of the control buttons on a control panel are of the entrance-exit type for controlling the power operation of track switches to establish different routes and thereafter causethe clearing of the signals governing such routes.

In a system of the entrance-exit type, the control' panel'preferably comprises a miniature track diagram with suitable control buttons, or the like, located at points on the track diagram corresponding to the signal locations constituting the entrance and/or exit ends of the various routes. To establish any given route, all that is required is the operation of a control button for the entrance end of that route followed by the actuationof a control button for the exit end of such route, the track switches being operated to' positions as required followed by the clearing of the governing signal for that route. It is to be understood that in such a system auxiliary control levers may be provided to individually control the various track switches under certain emergency conditions.

The manipulation of the control. buttons to designate the entrance and exit ends of any desired route causes the, automatic selection and operation of all the track switches or cross-overs involved in such route. This automatic operation of the system is effected by suitable route establishing means comprising in the system of the present invention initiation and completion circuits. The operation of a button to designate the entrance end of'a route energizes the initiating circuits to preselect the positions of the various switches for each of the available routes originating at such entering signal locations; while the subsequent operation of a controlbutton to designate the exit end of any given one of such available routes originating at the d'esig nated entrance point energizes the completion circuits to energize suitable normal and reverse control relays for the various switches in such given route in accordance with the preselection operation.

The application of such a system as above outlined, to a terminal or large interlocking plant involves in effect the provision of a plurality of interlocking systems which must be inter-related so as to establish what are conveniently termed through routes'extending through the entire interlocking plant.

Thus, for convenience in: the discussion ofithe present invention, any group of track. switches and crossovers whichprovide inter-related routes and which are located between or bounded by their governing signals may be termed an interlocked group, and a large terminal usually com.- p-risesa plurality of such interlocked groups.

As above mentioned, a terminal or interlocking plant may include one orseveral of. these interlocked groups dependent upon the arrangement and size of the track layout and the movements of traific to be made thereover; and some of such interlocked groups maybe located end-toend so as to provide one or more through routes? past the signals ofone or more interlocked groups, which signals then" become in effect intermediate signals with respect to any given through route;

When an entrance-exit type of control system is applied to a terminal or interlocking plant involving several interlocked" groups which may provide various through routes, it is desirable to have thesystem so organized as to effect the establishment of a through route by merely actuating the control button for the entering signal location followed by the actuation of the control button for the exit end of a through route without manipulating the control buttons for the intervening intermediate signal locations.

Such a switch and signal control system has been disclosed, for example, in the prior application of A. Langdon, Ser. No. 119,641, filed January 8, 19.37; in the patent granted to Wight and Langdon,.Patent No. 2,219,502, datedOctOber 29; 1.9140; and also in the prior application ofJudge, Ser. No. 330,535; filed April 19, 1940. The present invention is in the nature of an improvement in the means employed for accomplishing the desired functions and results in such a type of system providing, through route control; and no claim is made herein to anything disclosed in such prior applications.

One object of the present invention is to provide a system of this character, where the designation. of an entering signal. location preselects the positions of those switches in all of the various available routes. and. through routes originating at suchentrance point in such a manner that this preselection operation effected by the energization of. initiating.circuitswillnotextend over the initiating. circuit for a. route occupied by a train.

Another object of the present invention is. to provide such limitation of the preselectionopera tion to-theunoccupied routes when an entrance point is designated to-govern a high speed signal orqa semi-automatic-dwarf signal, but to permit the preselection operation for all routes in any given interlocked group irrespective of their occupied conditions when the entrance point is designated to govern a call-on or low speed signal. This preselection operation for a low speed signal is not efiective for the through routes originating at such entering signal location, as the call-on signals thus controlled are used to facilitate switching train movements within their own interlocked group and are not intended to govern A further object of the invention is to so ori.

ganize the system that when a signal location is designated as an entrance point for a high speed or semi-automatic dwarf signal, that the preselection operation will extend to only those exit points which are included in through routes, and

the subsequent designation of some exit point to whicl'i a tlnougn route does not cxend rails in the establishment of such route, while on the other hand the manipulation of the control button for such entrance signal location in a manner characteristic of a call-on or low speed signal permits that entering signal to be cleared for any possible route within its own interlocked group.

A further feature of the invention is to effect the above mentioned objects in such a way as to give a predetermined preference between the several optional or alternative routes afiorded by the track layout between the same entrance and exit points irrespective of whether such entrance and exit points are in the same interlocked group or are for some through route aiTorded by the track layout. In the event the superior or preferred alternative route cannot be established due to the establishment or occupancy of a conflicting route, then the next more inferior alternative route will be automatically established.

Other objects and characteristic features of the i e ion o means em loyed to enable the operator to cancel a route partially or completely set up by merely actuating in a distinctive manner the control button at an entrance end of such route; to provide for individual operation of any switch by the manipulation of an auxiliary switch control lever; and to so organize the system that the display of suitable desirable indications may be readily effected by means not disclosed in the present application but disclosed in prior applications such as in the application of T. J. Judge, Ser. No. 330,535, filed April 19, 1940.

The nature of the invention and complexity of the structural organization and its mode of operation makes it diflicult to define the invention completely and yet briefly; therefore other various characteristic features, attributes, and advantages of the system embodying this invention will be discussed in detail as the description progresses.

The accompanying drawings illustrate conventionally and diagrammatically a specific embodiment of the invention applied to a typical or representative track layout, the parts and circuits illustrated being arranged in a manner to facilitate an explanation and an understanding of the invention rather than to show specifically how the various relays and devices may be arranged and structurally organized in actual practice, and various symbols nomenclatures are employed to simplify this diagrammatic illustration.

Figs 1A, 3D and 1E, when placed side by side, show diagrammatically a control panel having a track diagram together with the associated route establishing means for a track layout corresponding to the track diagram and typical of the various arrangements of signals and crossovers that may be found in actual practice;

Fig. 2 shows a typical switch control circuit which illustrates how each of the track switches of the track layout chosen for the present embodiment may be controlled either by the automatic operation of the route establishing means or by individual auxiliary lever operation;

Fig. 3 shows the track layout of the interlocking plant chosen as typical for the purpose of disclosing the present invention, and for which the miniature track diagram of Fig. 1A is provided, and this Fig. 3 also shows the signal selecting circuits provided to select and control the signals in accordance with the route establishing means and in accordance with traffic conditions in the track layout.

Fig. 4 shows the directional stick relay circuits with associated thermal relays for providing sectional release locking for the track switches as well as the approach locking circuits with suitable time release means;

Fig. 5 shows the locking relays for the various switches of the track layout;

Fig. 6 illustrates a typical signal mechanism of the search-light type and the associated repeating relays.

Figs. 7A and 7B illustrate a modified form of the invention.

Fig. 8 illustrates a modified form of the polarity responsive devices associated with certain track relay contacts.

In order to facilitate the disclosure of the present invention, the various parts and circuits have 7 been shown diagrammatically and certain conventional illustrations have been employed. Thus, the various devices, relays and their contacts are illustrated in a conventional manner, certain circuit details well known to those familiar with the art are merely indicated by dotted lines; and symbols are used to indicate connec- +=nw- 4-, HM: n -i fis of batteri s. or other sources of electric current instead of showing all of the wirin connections to these terminals.

The symbols (4-) and are employed to indicate the positive and negative terminals resnectively of suitable batteries or other sources of direct current. and the circuits with which these symbols are used always have current flowing in the same direction as graphically illustrated by the arrow heads and tails. If alterhating current is used with these circuits instead of direct current, the symbols shown are to be considered as representative of the instantaneous relative polarities of such current.

The symbols (13+) and (B) are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of direct current having a central or mid-tap indicated by the symbol (CN) The sources thus indicated are used to provide for the reversal of current flow in the circuits with which they are employed, and when such sources are used in connection with line circuits, it is assumed that the .4. 5 and F5 as well as a single switch 3.

mid-taps (CN) are connected over suitable com mon return line wires.

GENERAL ORGANIZATION or The SYSTEM It is of course well understood that the switch and signal control system of the present invention will govern the power operation of the switches and signals at the track layout in the field from a central tower or control ofiice. The control oflice will include a suitable control machine provided in accordance with the present invention, which control machine is directly connected to the various power operated track switches and signals by suitable line wires. Inasmuch as the distribution of the apparatus between the control oflice and the track layout would in practice vary in accordance with the different circumstances involved, no effort has been made to distinctly point out where the dividing line exists between the field and control ofiice ap- ,paratus.

However, it may be well to state that direct line wire control is contemplated and that most of the apparatus is located in the control otiice with line wires extending to the switches and signals. On the other hand, much of apparatus might well be located in a bungalow adiacent the track layout and suitable direct l ne wires or code type communication. system be used to connect the control machine with such bungalow. Such a code type system has. been disclosed, for example, in the prior patent of Preston and Hitchcock, Patent No. dated September 6. 1.938. This has been pointed out for the purpose of having it understood that '1 the features of the present nvention may be applied to any switch and si nal control system of the entrance-exit type irrespective of the tyne of system employed to communicate between the control oilice and the track layout.

Track layout (F11 3) An interlocking plant may include one or several interlocked groups, it beingunderstood that an interlocked group comprises one or more track switches for settinrr up difierent routes together with signals for overnin traffic thereover. The track layout of Fig. 3 illustrates an interlocking plant havine two such interlocked groups located on the main line of a double track railroad with automa ic block signals assumed to be outside of the yard l mits. It is of course to be understood that the present invention. be practiced without the associated automatic signal system outside of the interlocking plant. and it is also to be understood that the pre, invention maybe applied to an interlocking plant having many more interlocked groups. the present disclosure serving to show the manner in which two adjoining interlocked groups are inter-related which. inter-relation may be considered typical of the inter-relation for any other two adjoining interlocked roups.

With reference to Fig. 3 of the accompanying drawings, the track layout includes crossovers 2,

track switch is assumed to be equipped with a power operated switch machine SM and cross- :over usually has a power operated switch machine for each of its opposite ends. These switch mach nes may be of suitable character. such for example, as disclosed in the patent to W. K.

'Howe, Patent No. 1.466.963, dated September 4,

.1923. Each switch machine SM is controlled in a manner suitable for remote control by a seccen ral normal deenergized position.

ondary switch control relay WZ (see Fig. .2) through suitable overload protection and the like, such as shown, for example, in the patent to W. H. Hoppe et al., Patent No. 1,877,876, dated September 20, 1932. It will be assumed, for convenience, that any given secondary switch control relay WZ of the present disclosure is to be used for remotely controlling the polar relay 1 CR, illustrated in the Hoppe et al. patent, which relay CR is local to its associated switch machine.

The control of the switch machines of a crossover, such as crossover 2 for example, has been typically illustrated in Fig. 2 of the accompanying drawings and each such track switch or crossover has its position and locked condition indicated by a relay NP whichis suitably controlled to one energized polar position or the other dependent upon the normal or reverse position and locked condition of its associated switch points. This control of the relay WP for any switch is effected through the use of suitable point detector contacts controlled as disclosed for example in the patent to C. S. Bushnell, Patent No. 1,517,236, dated November 25, 1924. In the case of a crossover of the usual type, each end of the crossover has its associated point detector mechanism and the circuit for the single switch position repeating relay WP is suitably selected through the contacts of both mechanisms.

Suitable wayside signals are shown in Fig. 3 for governing the high speed traflic and also for facilitating switching train movements in the plant. Although any type of signals may be employed giving suitable indications appropriate for the type of traffic to be governed, it has been assumed for the purpose of the present disclosure that search-light signals are employed and that high speed trafiic may move in either direction on both tracks. Thus, high speed signals HA, IZA, 15A and lliA are shown for governing high speed trafiic to the right; while signals HA, !8A, BA, MA, 20 and 2! are for governing high speed traflic to the left. Low speed traflic to the right is governed by signals 10, HB, I23, I53 and 163; while low speed traflic to the left is governed by signals HB, IBB, I313 and 14B. Signals 20 and 2| are assumed to be high speed automatic signals governing trafiic into automatic block signal territory to merely illustrate the manner of relating an interlocking plant of the present invention to such territory. The high speed signals are so controlled as to indicate clear (green), caution (yellow), and stop (red), while the low speed signals are arranged to indicate caution (yellow), and stop (red). Each of these signals has been assumed to be of the type disclosed, for example in the patent to O. S. Field, Patent No.

1,835.150, dated December 8. 1931, and one such mechanism has been diagrammatically illustrated in 6 of the drawings.

Referring to Fig. 6, the signal mechanism includes an operating winding 24 which may be energized with one polarity or the other to move its rotor 25 to the right or to the left from a When the rotor 25 is in a neutral deenergized position, a red color screen or roundel r positioned in vf ont .of the illum nated lamp 25 so as to 'ause position a yellow roundel y in front of the lamp 26; while if positive potential is applied to the upper terminal of the Winding 24, the rotor 25 is moved in a clockwise direction to position a green roundel g in front of the lamp 25 to give a green indication.

When the signal is deenergized the contacts 2'! and 28 assume normal positions as shown for energizing the red repeater relay RGP associated therewith over an obvious circuit; but, if the rotor is moved in a clockwise direction the contact 2i is opened, or if the rotor is moved in a counterclockwise direction the contact 28 is open, so that the relay RGP is deenergized Whenever the signal displays anything other than a red indication. When the signal displays either a green or a yellow indication, the contacts or 2.? are moved to operated positions respectively, in which obvious circuits are closed for the green and yellow repeater relay GYP.

Each of these signal mechanisms is controlled by its associated signal control relay G, as for example, the signal ii! is controlled by a signal control relay lilG, signal HA is controlled by relay HAG, While signal MB is controlled by relay l 23G. The circuits for these various signal control relays G have been shown in Fig. 3; while the typical manner in which such a relay controls its signal has been-shown in Fig. 6. However, these connections between the various signal control relays G and their signals has been indicated bysuitable legends in Fig. 3.

It will also noted that the signal control circuits and signal control relays G shown in Fig. 3 are for the signals of the left-hand interlocked group of the track layout, it being understood that similar signal control relays and associated circuits would also be provided for the right-hand interlocked group.

The track layout of Fig. 3 is also assumed to be provided with suitable detector track sections having the usual track relays and track batteries, but for convenience the various track sections have merely been designated by suitable nomenclature such as sections 2T, 3T, 4T, 5T, etc., and each of these sections are assumed to have a corresponding track relay, such as track relays ZTR, 3TB, 3TB. 5TH, etc. It is contemplated that suitable detector, approach and sectional rear release route locking will be provided, such as disclosed in the prior art, as for example, in the prior patent of C. F. Stoltz. No. 2.125511, dated April app oach locking has been shown for convenience Control ojfice apparatus With reference to Fig. 1A, it is contemplated that the control machine has a control panel i h a e cl. dia am located ther o co res onding to the actual track layout of Fig. 3. There is also assumed to be suitable means efifective, when a route is established. to illuminate corresponding portions of the track diagram. Suitable control buttons of the self restoring push button type, such as shown for example, in the prior application of J F. Merkel, Ser. No. 158,720, filed August 12, 1937, are located at points on the track diagram corresponding to the various signal locations in the actual track layout. Each of these control buttons is assumed to be of thespring return. type, so constructed as to be capable of being pulled outward y to an off normal position as well as being capable of being depressed to an operated position. Certain of the buttons, such as where call-on or low speed signals are also provided, are arranged to be rotated to right or lefthand operated positions from which they must be manually restored to normal. These control buttons are suitably designated IONB, IINB, IZNB, etc. to indicate that such buttons are associated with the signal locations I I], II and 12 for designating such locations as entrance points, and suitable arrows are located thereon to indicate the direction of trafilc governed by the corresponding signals. It is also assumed that the signal indicator lamps are located within the entrance buttons NB, but such indicators have not been shown for the sake of simplicity.

Other control buttons of the self-restoring push button type, such as IGXB, HXB, IZXB, etc. are provided to designate the exit ends of the various routes and these buttons govern traflic in directions indicated by the arrows located thereon. The switches and signals are suitably identified on the control panel by letters or numbers, or other designations, which will provided ready means of reference for the operator.

Each of the track switches also has an associated auxiliary control lever SML on the control panel. These levers have been shown in Fig. 1A, but only a typical lever ZSML and its associated control circuits for crossover 2 has been shown in Fig. 2.

The control buttons for each of the entrance and exit signal locations have associated therewith suitable relays for controlling the route establishing means. More specifically, each entrance button NB has associated therewith an entrance relay NR, and if such entrance button is to be used to designate an entrance signal location as either a high speed or a low speed entering signal location, then two such entrance relays are provided and are respectively designated NR and CNR. For example, the button ll NB has associated therewith relays HNR and HCNR. Each exit button XB has associated therewith an exit relay XR. For example, the button HlXB has associated therewith the relay IDXR.

The route establishing means of Figs. 1A to IE includes primary switch control relays and pre-- selecting relays for each of the track switches and crossovers. For example, the switch 3 has associated therewith the preselecting relay 3Y and the primary switch control relays 3N and 3R, or in other words, three relays are associated with the single switch 3. On the other hand, the

crossover 2 has the preselecting relays ZAY and ZBY associated therewith as well as the primary switch control relays ZAN, 2R and ZBN, or in other words, each crossover requires five such relays.

For the purpose of effecting the through route control provided by the present invention there are relays NP and XP associated with the signal locationsv which may become intermediate signal locations in some through route.

Route establishing means (Figs. 1A1E) When an operator desires to establish a route, he actuates the entrance button NB for the entering signal location which causes the entrance relay NR or CNR. for that location to be picked up which in turn appliesenergy to the initiating circuits for each of the routes originating at that signal location.

The energization of the initiating circuits by the picking up of the entrance relay NR or CNR causes the preselection of the trailed switches in such routes by the selective energization of relays AY and/or BY as the case may be. Any one of these routes that is available for use may then have its exit relay XR picked up by the actuation of its exit button KB.

The picking up of the exit relay XR. for the exit end of any given available route having its entrance relay NR picked up causes energy to be applied to the completion network for energizing the primary switch control relays over completion circuits as required to establish that given route, and in accordance with the preselection operation effected by the energization of the relays AY and BY.

In general, the route establishing means comprises a network of initiating circuits for both :directions, that is, there is an initiating network for traflic to the right which has feed points for each of the signal locations governing trafiic to the right, and similarly there is an initiating network for traffic to the left having feed points for each of the signal locations governing traffic 'to the left.

There are completion circuits for both directions of traffic each having feed points at the signal locations corresponding to the exit ends of the various routes, but the circuits are so organized and inter-related as to employ but one winding for each of the primary switch control relays.

Following the operation of the track switches of any given. route having its entrance and exit ends designated, the signal at the entrance end of such route is cleared to allow the passage of a train. The signal control circuits for the left-hand interlocked group are shown in Fig. 3

of the drawings, and are so organized, that not only does each track switch of any given route have to bein a proper position in correspondence with its individual control, but all of the track switches must have properly responded to conform to the route having its entrance and exit relays picked up.

We will now consider in detail the manner in which the system of the present invention responds to the actuation of entrance andexit buttons N13 and KB to effect the establishment of a route between the corresponding signal locations.

Entrance operation With the system inthe normal condition illustrated inthe drawings, the pushing of an entrance button, such as button I3NB (see Fig.

1D), causes its associated entrance relay I3NR. to be picked up by reason of a circuit closed from through a circuit including front contact 29 of track relay 4TB, contact 30 of entrance button l3NB in a depressed position, back contact 3| of entrance relay I3CNR, windings of relay IENR, back contact 32 of entrance relay I5CNR, back contact 33 of entrance relay IENR,

'trance relay IBCNR, back contact33 of entrance =re1ay I5NR, to

the entrance relay I3NR energized dependent This stick circuit maintains upon the track relay 4TB, although the opercator releases the entrance button l3NB. lniother 75 words, the entrance of a train onto the track section 4T immediatelyin advance of the signal 13 automatically restores the entrance relay 'I3NR to a deenergized condition. Also, theoperator may .manually restore the entrance relay i3NR by merely Pulling the entrance button I3NB so as to open the contact .30 included in its stick circuit.

This actuation of the entrance button I3NB to a depressed position from which it is selfrestaring,is for the clearing of the upper arm signal "l'ZiA, so that the entrance relay IBNR appliespositive potential (B-i through its front contact to the initiating circuits for all of the routes originating at that signal location.

On the other hand, if the operator desires to clear the lower arm or low speed signal I3B instead or signal 13A, he rotates the entrance button l-3NB in a clockwise direction to close an energizing circuit for the entrance relay E3CNR from through a circuit including contact segment 5| of entrance button I3NB in an operated position, back contact 52 of relay 'I3NR, windings of entrance relay IBCNR, back contact 32 of entrance relay ISCNR, back contact 33 of entrance relay I5NR, to This energization of the entrance relay |3CNR causes negative potential (3-) to be applied to the initiating circuits for all of the routes originating at corresponding signal locations.

It is noted that relays 3NR and I3CNR are interlocked'by contacts 3| and 52 so that only one of these relays can be energized at any one time.

Preselecting and conditioning operation The picking up of the entrance relay |3NR applies energy (B+) to the initiating circuits for each of the routes originating at the signal I 3. More specifically energy is applied from (B+), through a circuit including front contact 35 of relay I3NR, back contact 36 of relay I3CNR, back contact 3lof relay ISNP, back contact 38 of relay I3XR, wire 39 (Figs. 1D, 10 to 1B), back contact 40 of relay 4R, windings of relay HAY, to (ON).

The response of the relay 4AY passes energy on from its right-hand terminal through its front contact 4i, front contact 42 of track relay 4TH, back contact 43 of relay 3R, wire, back contact 45 of relay 2R,'windings of relay ZAY, to (ON).

The response of the relay ZAY to such energization passes energy on from its right-hand "terminal through its front contact 45, front contact *4! of track relay 3TB, to the right-hand terminal of the exit relay HXR. Thus, the relay IXR. is conditioned for energization if its exit button I [m is'actuated.

The picking up of the relay 4AY also passes energy from its right-hand terminal through its front contact 4|, front contact 42' of track relay :4TR, back contact 38 of relay 3N, wire 49, to the rectifier unit 50. But the rectifier unit is so located in the circuit as to prevent theflow of positive energy (3+) to the exit relay -IOXR. In other words, the exit relay IGXR -is not conditioned for energization if the exit button I'OXB is-operated, because the energy applied upon the actuation of the entrance button ISNB is of a polarity'associated with high speed routes. However, if the entrance button i3N'B i operated to a rotated position for clearing a low speedsignal, negative potential (B) is applied-to the-initiating circuits described above and energy would pass through the rectifier unit 58 conditioning the exit relay IUXR. The exit relay IIXR would also be conditioned by this negative energy. In other words, the route from signal I3 to signal 10 is a low speed route while the route from signal l3 to signal H is for both high and low speed traffic.

Emit operation Assuming that the operator has rotated the entrance button I3NB, then a route can be established either to signal H) or to signal H by merely actuating the corresponding exit button XB. If he actuates the exit button IQXB, ener y passes through the rectifier unit 50] to the righthand terminal of the exit relay IOXR, winding of relay HJXR, back contact 53 of relay IBNR, actuated contact 54 of relay IUXB, to (ON). As soon as the exit relay IOXR picks up, it closes its front contact 55 to complete a stick circuit by connecting the mid-tap (CN) to the left-hand terminal of relay IBXR.

On the other hand, if the operator actuates the exit button I IXB, energy passes from the heel of contact 46, through front contact 41 of track relay 3TH, windings of exit relay HXR, back contact 10 of relay HNR, back contact H of relay HCNR, actuated contact 12 of exit button IIXB, to (CN). As soon as the relay IIXR picks up, it closes front contact 53 to connect (UN) to its left-hand terminal sothat the relay HXR is maintained energized independently of the release of the exit button HXB.

It is of course understood that only one of the routes can be established at any one time, so that the operator will actuate either the button HIXB or the button IlXB depending upon the particular route desired. The operation of the exit buttons for both routes has been pointed out for the purpose of making it more clear that conditioning energy is supplied to the exit relay XR. for the exit end of each available route originating at the designated entrance point.

Completion operation The response of an exit relay XR to the actuation of its corresponding button occurs only if a route terminating at the corresponding exit point is available for use, so that the response of such exit relay XR can immediately apply energy to the completion circuits for picking up the primary switch control relays for the switches in the corresponding route.

Assuming that the operator has actuated the buttons I3NB and lilXB, and that the relay IUXR. is picked up, a circuit is then closed for picking up the relay 3R from through a circuit in cluding front contact 56 of relay HJXR, wire 51, back contact 59 of relay 3N, winding of relay SE,

The response of the relay 3R passes energy on from its left-hand terminal through its front contact 60, front contact 6| of relay 4AY, upper winding of relay 4AN, to

The response of the relay 4AN passes energy on from its left-hand terminal, through its front contact 62, front contact 53 of relay 4AY, wire 64, (Figs. 13, 1C, 1D), winding of relay I3XP,

back contact 65 of relay E3XR, to The relay I3XP is employed in connection with the control of through routes and its operation is not pertinent to the establishment of this particular route between signal l3 and signal l0.

On the other hand, if the operator has actuated the buttons IBNB and I IXB. the response of the exit relay IIXR applies energy to the completion circuit for picking up the relay ZAN from through a circuit including front contact 14 of relay HXR, front contact 75 of relay ZAY, windings of relay 2AN, to

The response of the relay ZAN passes energy on from its left-hand terminal through its front contact 76, front contact H of relay ZAY, wire 18, back contact 19 of relay 3Y, windings of relay 3N, to

The response of the relay 3N passes energy on from its left-hand terminal through its front contact 88, back contact 8| of relay 3Y, front contact 6| of relay 4AY, windings of relay 6AN, to The response of relay 4AN passes energy on to the relay ISXP as above pointed out.

It will thus be seen that the operation of an entrance button causes the initiating circuits to perform a preselection operation and to condition the exit relays for the exit ends of the various available routes originating at such designated entrance point. The response of an exit relay to the actuation of an exit button then effects a completion operation to energize the primary switch control relays for the switches in a particular one of such available routes to be operated in accordance with such preselection, and these primary switch control relays then cause the establishment of the desired route.

The response of the primary switch control relays to the energization of the completion circuit network is also effective to complete the interlocking operation between routes which conflict with the route then being established. More specifically, the response of the relay AN opens back contacts 82 and 66 in the initiating circuits so that no energy can be supplied over the initiating circuit portions corresponding to the crossover 4 reversed. Also, back contact 83 of relay AAN opens the completion circuits for relay 4R insofar as the supply of energy to such relay can be effected from exit points at the lefthand end of this interlocked group.

If the route is established from signal 13 to signal I0, then the picking up of the relay 3R. opens back contact 43 which deenergizes the relay ZAY and removes potential from the exit relay HXR.

On the other hand, if the route is established from signal Hi to signal H the picking up of the relay 3N opens back contact 48 removing potential from the exit relay lOXR.

In other words, the preselection operation which has been performed for all the routes originating at the signal location corresponding to the actuated entrance button, is cancelled for all of such routes except the one selected by the actuation of its exit button. This provides that any switches not included in the selected route may be employed in any possible routes that are not in conflict with the selected route.

It is of course obvious that the picking up of the primary switch control relays 2AN, 3N and 4AN for establishing the route from signal l3 to a signal II, for example, opens their respective contacts in the initiating circuits in a manner to completely interlock that route against the establishment of any conflicting route.

Typical switch control (Fig. 2)

The picking up of any primary switch control relay, such as relay ZAN, for example, causes the operation of the associated switch machine, or switch machines, as the case may be. The pickup circuits for the primary switch control relays have been shown n Fi s. lA-lE. but; the ntrol circu ts ov ne by uch relays and their stick circuits have been typically shown in Fig, 2 with respect to the control relays lAN-2Rr.-2BN for the crossover 2..

With the track switches of the crossover 2 in normal positions, the relay ZWP is energized with a normal polarity so that its contacts assume normal positions. While the primary switch control relays 2AN-.2R.2 BN are deenergized, the correspondence relays ZNCR and ZRCR. are also dee-nergized, but the picking up of a primary Switch control relay, such as 2AN,,with. the track switches already in normal positions, immediately causes the1 energization of the normal correspondcnce relay Z-NCR, and the secondary switch control relay 2W2 remains, tie-energized as no switch operation is required under such circunistances. The same is true with regard to relay 2BN. Similarly, if the track switches are standing in reverse positions and the relay ER is picked up, the relay 23GB, is immediately energized and the relay 2W2 remains deenergized as no switch operation is. required under such circumstances.

But whenever a. switch operation is required in response to the energization. of a primary switch control relay, the secondary switch con.- trol relay 2WZ is energized and maintained en.- ergized until the switch or switches have .operated into correspondence with their primary switch control relays after which the switch con-. trol relay ZWZis deenergized allowingthe proper correspondence relay to be picked up. With this sequence of operations, it is then possible to select the signal control circuits through con- 1 tacts of the correspondence relays ZNCR and ZRCR with the assurance that the track switches are in the proper positions and operating energy has been removed therefrom before a signal can be cleared.

It is noted. that the lock relay 3L is normally energized by a circuit closed from and including front. contact 34 of relay 3E8, front contact 8.5 of relay 3TH, front contact 86 of relay: 3W8, windings of 3L, to Similarly, the lock relay 91.- is normally energized by a: circuit closed from and including front contact 8."! of relay 9ES,.front contact 88 of relay 9TB, front contact 89. of relay SWS, windings of relay 9L, to It is noted that these same circuits have also been shown in Fig. 50f. the accompanying drawings together with the other lock relays 4L and IGL, and have been repeated in thisFig. 2 for convenience in the consideration of the switch control circuits. It is of course understood thatthe directional stick relays ES and WSare controlled as shown in Fig. 4 so as to be dropped away only after the route has been established and the signal control relay picked up.

Assuming that the track switches of crossover 2 are in normal positions and the relay ZAN. is picked up, the normal correspondence relay. ZNCR is energized by a circuit closed from (+),v including front contact 90 of relay 2AN, polar contact 9! of relay ZWP in a right-hand position, front contact 92 of: relay 2WP, back contact 93 of relay 2WZ, windings of relay ZNCR, to If the relay 2BN is pickedup instead of the relay ZAN, then front contact 94 is closed to supply energy to the circuit just pointed out through back contact 90.

Let us assume that the primary switch control relay 2R is picked up (although the manner of its energisation has not been specifically de- 36 of relay ZWP in a right-hand position, front I contact 9! of relay 9L, front contact 98 of relay 3L, lower winding of relay ZWZ, to Thep-icking up of the neutral contacts 99 and I together with. the actuation of the polar contacts H31! and 1522 to left-hand reverse controlling positions, applies a proper polarity to the switch machines 2ASM and 2BSM to cause their reverse operation in the well known manner. When the track switches are unlocked, the relay 2W1 is; of course deenergized so that the polar contact 96. is shunted by back contact H13. Upon the completion of the operation of the track switches of crossover 2 to reverse positions, the relay EWP is supplied with the opposite polarity actuating its polar contacts to left-hand positions and picking up its neutral contacts. However, the polar contact 9 8; is shunted by back contact its; so that the relay ZWZ is maintained ens-r zed until the relay EWP is fully energized to pick up its neutral contacts. When this has been effected the relay ZWZ is deenergized and a circuit is then closed for the reverse correspondence relay ZRCR from. and includi:;g back contact 96 of relay 2AN, back contact ofrelay 2BN, front contact of relay 2R, polar. contact. contact of relay ZWZ, windings of relay ERCR, to

Letus assume that the track switches of crossover are in reverse positions and that the relay- ZAN is energized to. operate them to normal positions, then the relay ZiWZ is energized over a circuit from and including a front contact 919 of relay ZAN, polar contact 94 of relay ZWP in a left-hand position, front contact I33 of relay. 9L, front contact MW of relay 3L, upper winding of relay 2W2, to During the operation of the track switches the relay 2W? is deenergized closing bank contact Hi8 tov shunt the polar contact 9-1. The track switches of crossover 2 are of course operated to normal positions while the relay contacts 99 and I00 of relay ZWZ arev picked up and its polar contacts Ill! and H32 are in right-hand normal controlling positions. At the end of the operation of the switches to normal positions, the relay ZWZ is deenergized closing back contact 93. to allow the energization of the correspondence relay ZNCR over its circuits previously pointed out.

If for some reason the primary switch control relays 2AN2R2BN are deenergized during a switch controlling operation insofar as the entrance-exit route e control. ci ar-- d, the secondary sv ch ntrol relay 2W2 is, in -tained energised irre...,.w. ive oi iheplimary.

switch control relays to complete the switch operation already initiated. This is effected by local energizing circuits. Assume that the track switches of crossover 2 are being operated to reverse positions, then the relay 2W? is. deenergized but its polar contacts are in the normal positions shown and the relay 2WZ has been energized so that its polar contacts are in lefthand reverse controlling positions and its neutral contacts are picked up. If the relay 2B is de-v ener-gized before the. operating stroke is come.

of relay ZWP in a left-hand. position, front contact Hi l of relay 2W1, back pleted, then the relay ZWZ is energized by a circuit closed from and including front contact I09 of relay 2W2, polar contact III!) in a left-hand position, back contact I03 of relay ZWP in multiple with polar contact 95 in a righthand position, front contact 91 of relay 9L, front contact Q8 of relay 3L, lower winding of relay 2W2, to When the switch machines 2ASM and QBSM have operated the switches of crossover 2 to reverse positions, the relay 2WP is of course energized with the proper polarity to actuate its contacts to left-hand positions picking up the neutral contact I03 which deenergizes the relay ZWZ. The correspondence relay ZRCR is not energized because the primary switch control relays are deenergized.

On the other hand, if the track switches of crossover 2 are in reverse positions and are being operated to normal positions by relays ZAN and/ or 2BN, then a similar circuit for maintaining relay 2WZ energized in a normal controlling position is closed from including front contact I 09 of relay 2WZ, polar contact Ilfl of relay ZWZ in a right-hand position, back contact I88 of relay ZWP in multiple with polar contact 9| in a left hand position, front contact I06 of relay 9L, front contact I01 of relay 3L, upper winding of relay 'ZWZ, to The completion of the operation of the track switches to normal positions of course energizes the relay ZWP with the proper polarity to actuate its polar contacts to right-hand positions and pick up its neutral contacts including contact N38 to deenergize the relay ZWZ. The correspondence relay ZNCR remains deenergized as the primary switch control relays are all deenergized.

The switch control circuit is so organized that even though the primary switch control relays are deenergized and the secondary switch control relay is also deenergized, the accidental movement of the track switches away from their normal or reverse positions automatically causes the restoration of such switches to the positions to which they were last controlled. The same automatic operation occurs if the track switches are hand cranked out of their last controlled position and their control circuits again closed. It is understood that the insertion of the hand crank of course opens the local operating circuit of the switch machine motor so that the switch may be cranked to an opposite position, and power is not applied to the switch machine motor until the crank is removed.

When a switch is hand cranked out of a normal or a reverse position, or is accidentally moved out of such positions, its associated relay WP is of course deenergized which efiects the closure of an energizing circuit for the secondary switch control relay WZ to actuate such relay to the last controlled position as determined by the position of the polar contacts of the associated WZ relay. This can be done as the polar contacts are of the magnetic stick type and remain in their last actuated position. When the relay WZ is thus energized (assuming the crank to be removed), power is applied to the motor and the track switch or switches involved are restored to their last controlled position.

More specifically, assume that one or the other or both of the track switches associated with the crossover 2 are hand cranked or accidentally moved out of their normal positions deenergizing the relay ZWP, then a circuit is closed for energizing the relay 2W Z to a normal controlling position from including back contact of 75 relay ZAN', back contact 94 of relay 2BN, back contact 95 of relay 2R, back contact III of relay ZWP, polar contact III] of relay ZWZ in a righthand position, neutral contact I08 of relay ZWP, front contact I06 of relay 9L, front contact IU'I of relay 3L, upper winding of relay 2W2, to If the switches are accidentally jarred out of locked normal positions then the normal control immediately becomes elTective to restore them to such positions at which time the relay ZWP is reenergized and opens back contact HI deenergizing the relay ZWZ.

It is obvious that a similar operation would occur if the track switches were standing in reverse positions, by reason of the back contact I I I of relay 2WP applying energy to the polar contact I I0 so that with it in a left-hand reverse controlling position, the relay 2WZ is energized over its reverse energizing circuit,

The switch control circuits of the present invention are also organized so as to provide that the primary switch control relays may be energized by auxiliary switch control levers individual to their respective track switches and crossovers. This auxiliary control is interlocked with the entrance-exit route establishing control in such a way that the control first effected cannot be interrupted by the other.

More specifically, the relay ZAN can be energized by the actuation of the control lever ZSML to a normal controlling position from its neutral non-controlling position by reason of a circuit closed from including lever contact I I2 in a normal position, back contact H3 of relay 2R, lower winding of relay ZAN, to At the same time the relay ZBN is energized by a circuit closed from including lever contact II4 in a normal position, back contact II5 of relay 2R, lower winding of relay 2BN, to

On the other hand when the lever ZSML is operated to its reverse position, the relay 2R is energized by a circuit closed from including lever contact H2 in a reverse position, back contact II6 of relay ZAN, back contact II! of relay ZBN, lower winding of relay 2R, to

The energization of the primary switch control relays by reason of the operation of the auxiliary lever ZSML, effects the control of the track switch through the secondary switch control relay 2WZ in the same manner and over the same circuits.

above pointed out.

It may happen, when the primary switch control relays are being controlled either by the auxiliary lever dish/ill or by their entrance-exit controlled completion circuits, that it becomes necessary to reverse the operation of the switches in mid-stroke. It is obvious by consideration of the pick-up circuits controlled by the lever ZSML that the reverse relay 2R must be deenergized before the relays ZAN and ZBN can be picked up; and also the relays ZAN and ZBN must be deenergized before the relay 2R can be picked up. A similar interlock is provided in the, entrance-exit controlled completion circuits. In other words, the reversal of control may be effected providing the conflicting position does not have its primary switch control relay energized.

A change in the control present in the primary switch control relays is transferred to the secondary switch control relay ZWZ provided the associated lock relays 3L and 9L are energized. This reversal of control upon the. secondary switch control relay 2WZ is effected by neutralization of the control previously set up.

For example, if the secondary switch control relay 2WZ has been energized through its upper winding to cause the operation of the track switches to normal positions, then the relay ZWZ remains energized by reason of the stroke completing stick circuit including front contact I09 even though the primary switch control relay ZAN or ZBN is deenergized before the stroke is completed. If the reverse primary switch control relay 2R is then picked up, energy is placed on the lower winding of the secondary switch control relay 2WZ which causes a flux to be produced in the relay in a direction opposing the flux produced by the energization of the upper winding of the relay. In other words, both windings of the relay are energized, one through the stick circuit used to effect completion, and the other through the regular reverse control circuit. These opposing fluxes in the relay neutralize each other and cause the neutral contacts of the relay 2WZ to drop away. The opening of contact I09 deenergizes the stroke completing stick circuit for continuing the normal operation, and before the neutral contacts can again pick up the polar contacts assume positions in accordance with the energization effected through the reverse control circuit. When the neutral contacts then pick up front contact I09 merely applies to the stick circuit provided for the completion of the reverse operation of the switches. This drop away of the neutral contacts upon the neutralizing effect produced by the energization of both of the windings of the relay, followed by the response of the polar contacts to the energization of one winding alone before the neutral contacts can again pick up, is a characteristic of the usual polar neutral type relay employed for such secondary switch control relays Whenever a route is established over the track switches of a crossover (or over a single switch) such trackswitches are locked against operation by reason of the deenergization of the associated lock relay L, which look relay L not only opens contacts to prevent further energization of the secondary switch control relay WZ, but also closes stick circuits for the primary switch control relays in such a manner as to maintain an interlock between any conflicting routes including such track switches. In other words, the establishment of a route initially causes an interlock between that route and any conflicting routes and the presence of a train in such established route maintains that interlock although the control buttons have been manually restored or automatic restoration of the entrance relays has been effective.

For example, if a route is established between I signal I3 and signal II, the lock relay 3L is deenergized (as will be explained later) so that a stick circuit for the relay ZAN is closed from including back contact I I B of relay 3L, front contact lit of relay ZAN, front contact IIB of relay ZAN, lower winding of relay ZAN, to This stick circuit is closed irrespective of whether the relay 2AN has been initially picked up by the entrance-exit route establishing control or by the operation of the auxiliary control lever 2SML to a normal controlling position.

The primary switch control relay 2BN has a stick circuit controlled by the lock relay 9L by reason of a circuit from including back contact I45 of relay 9L, front contact I4! of relay ZBN, front contact II! of relay ZBN, lower winding of relay EBN, to This stick circuit is closed whenever a route is established over the crossover 2 in a normal position.

Whenever the crossover 2 is reversed and a route is established thereover, stick circuits are closed for the relay 2R whenever either or both of the lock relays 3L and 9L are deenergized. When the lock relay 9L is deenergized, a circuit is closed for relay 2R from including back contact I46 of relay 9L, front contact I49 of relay front contact II5 of relay 2R, lower winding of relay 2R, to

Another stick circuit for the relay 2R is closed while the lock relay 3L is deenergized from. including back contact I I3 of relay 3L, front contact #48 of relay 2R, front contact I I5 of relay 2R, lower winding of relay 2R, to

These stick circuits for the primary switch control relays which are closed upon the dropping of their associated lock relays, not only maintain the interlock between conflicting routes, but are also associated with the movement of the auxiliary switch control lever SML to a new controlling position while a route is established, so that such new control will not effect the control of the associated switch or switches to a new position upon the release of the locking of those switches. This is ordinarily termed the prevention of preconditioning and is sometimes called the electric lock equivalent.

For example, when a route established from signal I3 to signal H with the relay ZAN picked up, the stick circuit just pointed out is closed for relay ZAN with the lock relay 3L deenergized. This relay 2AN is thus maintained energized irrespective of the entrance-exit route establishing control. If the operator should for some reason move the lever ZSML to the reverse controlling position, this new control cannot be consumated either at that time or when the lock relay BL is picked up by reason of the fact that a stick circuit is closed from through lever contact H2 in a reverse controllin position, front contact I I8 of relay ZAN, lower winding of relay ZAN, to This requires that the lever ZSML must be restored to its neutral noncontrolling position before a new control can be effected for the track switches.

Similar stick circuits to prevent preconditioning are provided for each of the primary switch control relays, as will be obvious from a consideration of the circuits shown in Fig. 2, and due to such similarity they will not be pointed out in detail,

It is believed that the above description of the typical switch control shown in Fig. 2 may be readily applied to the control of any of the track switches or crossovers shown in the track layout selected for the embodiment of the present invention or to the track switches of any track layout found in practice.

Signal control circuits (Fig. 3)

After the track switches of a route have operated to proper positions for that route in response to the control of the route establishing means, the signal control relay for the signal location at the end of that route designated as the entrance point is then energized. As, for example, the route from signal I3 to signal II has the relays IQNR and I IXR, picked up if the operator has designated that route to be governed by the high speed signal I3A; but if the operator has designated such route to be governed by the low speed or call-on signal I3B, then the entrance relay I3CNR. is picked up instead of the entrance relay I3NR. Thus, upon the response of the track switches included in that route from signal It to signal II either the high speed signal I3A is cleared or the signal I313 depending upon the operators distinctive manipulation of the entrance button I3NB.

Assuming that the operator designated such route to be governed by the signal I3A, then an energizing circuit is closed for the signal control relay ISAG from including front contact I28 of relay IIXR, front contact I2! of relay 3TB, front contact I22 of relay ENCR, back contact I23 of relay ZRCR, front contact I24 of .relay 3NCR, back contact I25 of relay tRCR, front contact I26 of relay 4TB, front contact I21 of relay dNCR, back contact I28 of relay IIRCR, back contact I29 of relay IEXR, front contact I30 of relay I3NR, winding of relay IEAG, to

The picking up of contacts I3I and I32 of relay I3AG applies energy to the signal mechanism of signal ISA in a manner described in connection with Fig. 6, and such energy has a polarity determined by contacts I33 and H t of relay ZSIGYP. With the signal 20 at stop, the relay 2IlGrYP is deenergized so that the signal I3A is supplied with the proper polarity to cause it to indicate yellow or caution; while if the signal 20 is clear then the polarity applied to the mechanism of signal I3A is such as to cause it to indicate green or clear. The relay ZI'IGYP is controlled by the signal 29 in a manner typically shown in Fig. 6 for relay GYP.

It is of course to be understood that the operator can return the signal I3A to stop at any time by merely pulling the button IBNB to deenergize the entrance relay I3NR. Also, the passage of a train past the signal I3 causes the track relay 4TB to be deenergized opening front contact 29 (see Fig. 1B), which deenergizes the stick circuit for the entrance relay I3NR automatically restoring the signal I3A to stop.

On the other hand, if the operator had rotated the entrance button I 3NB to energize the entrance relay I3CNR to clear the call-on signal, then the signal ISB would be cleared by the energization of the signal relay I3BG.

More specifically, the relay ISBG has an energizing circuit under such circumstances from through a circuit including front Contact I35 of relay IIXR, front contact I36 of relay 2NCR, back contact I31 of relay ZRCR, front con-- I39 of tact I38 of relay SNCR, back contact relay 3RCR, front contact I40 of relay ANCR, back contact I4I of relay IRCR, back contact I42 of relay I3XR, front contact I43 of relay I3CNR, windings of relay IBBG, to The picking up of contacts IM and I45 of this relay ISBG applies energy to the signal mechanism I3B to cause it to indicate proceed at low speed.

This signal IZ'IB can be manually restored to stop by the rotation of the entrance button ISNB to its normal non-operated position. This effects the deenergization of the relay I3CNR in turn deenergizing the route establishing means and the signal control relay I3BG in an obvious manner.

The effect of the presence of a train in an established route upon the clearing of signals for that route will be discussed in detail hereinafter.

Route locking (Figs. 4 and 5) The embodiment of the present invention includes sectional release route looking as well as approach locking in Figs. 4 and 5 of the accompanying drawings. Each track section has associated therewith a lock relay L, an east directional stick relay ES and a west directional stick relay WS. Each signal location has associated therewith an approach locking stick relay AS together with a thermal time release relay TH.

Each of the locking relays L is energized through a circuit dependent upon the directional stick relays ES and WS for the associated track section (see Fig. 5). The circuits for lock relays 3L and 9L have been pointed out in connection with Fig. 2. The lock relay IL has a circuit from including front contact I55 of relay IES, front contact I5I of relay 4TR, front contact I52 of relay WVS, winding of relay 4L, to The lock relay IIlL has an energizing circuit closed from including front contact I53. of relay IEFES, front contact I54 of relay IilTR, front contact I55 of relay IllWS, windings of relay IEIL, to

The directional stick relays ES and WS have been shown in detail in Fig. 4 as well as the approach stick relays AS. Similar control circuits have been shown in general in th prior patent of C. F. Stoltz, Patent No. 2,115,511, dated April 26, 1938. However, for the purpose of clarity in the present disclosure, the circuits for the directional stick relays involved in the routes between signals II and I3 will be pointed out in detail.

The directional stick relay 3E8 associated with the track section 3T has an energizing .circuit closed from and including back contact I56 of the thermal relay IITH, back contact I51 of relay IIBG, back contact I58 of relay HAG, front contact I59 of relay IIAS, front contact Iiiil of relay 3TB, windings of relay 3E8, to Front contact I6I of relay 3E5 is provided to shunt the front contact Hill of its associated track relay STR.

The directional stick relay AES is provided with an energizing circuit from and including back contact I62 of thermal relay IIlTI-I, back contact 663 of signal relay IIIG, front contact Hit of relay IIlAS, front contact I65 of relay 3E8, front contact IE6 of track relay 4TB, windings of relay 4E5 to Front contact I61 of relay lES is provided to shunt the front contact I66 of relay 4TB.

The directional stick relay 4WS has an energizing circuit closed from and including back contact I68 of thermal relay I3TH, back contact I 69 of signal relay ISBG, back contact I10 of relay ISAG, front contact I1I of relay I3AS, front contact I12 of relay IIlWS, front contact I13 of track relay 4TB, windings of relay IWS, to Front contact I14 of relay 4W5? is provided to shunt th contact I13 of track relay ITR.

The directional stick relay 3W6 is provided with an energizing circuit closed from and including front contact I15 of relay IWS, front contact I16 of relay 9W8, front contact I11 of relay 3TB, windings of relay 3W8, to The front contact I18 of relay 3W3 is provided to shunt the contact I11 of relay 3TH.

It is noted that front contact I19 of relay INCR is provided to shunt the contact I12 oi the directional stick relay IQWS while the crossover 4 is in a normal controlled position, and similarly the front contact IBIl of relay 2NCR is provided to shunt the front contact I18 of relay BWS, while the crossover 2 is in a normal controlled position. These contacts of relays 4NCR and ZNCR prevent the establishment of routes on the track including track sections ST and II'JT from effecting the route locking associated with track sections 3T and AT, while the crossovers 2 and 4 are in normal controlled 

